Chamber spark-plugs with multiple igni- x



Feb. 11, 1958 F. SAUL CHAMBER SPARK-PLUGS WITH MULTIPLE IGNITION AND CENTER ELECTRODE Filed Aug. 28, 1953 JV l/ l llr United States Patent CHAMBER SPARK-PLUGS WITH 'MULTIPLE'IGNI- TION AND CENTER ELECTRODE Franz Saul, Gottingen, Germany, assignor to Walther Hem, Haiger-Dillkreis, Germany Application August 28, 1953, Serial No. 377,121

Claims priority, application Germany September 12, 1952 3 Claims. (Cl. 313-141) With every spark-plug two factors have to be contended with, namely oil and heat. The introduction of the chamber plug has brought considerable improvement as regards oil fouling, but the control of heat is not yet perfect. The different working conditions require spark-plugs with different thermal coefficients, and also two-stroke sparkplugs. For this reason it is understandable that hitherto a large number of differently constructed spark-plugs is required for different working conditions.

The object of the invention is to produce a chamber spark-plug with multiple ignition and center electrode, in which the known disadvantages are no longer present and which can be used equally well for all working conditions. After a considerable amount of experimenting it has been possible to develop a standard spark-plug which ensures sufiicient heat dissipation and in which the spark creepage paths at the foot of the insulator can no longer form; and this without it being necessary to make any alteration in the ignition system and carburetor or the like of the internal combustion engine.

This is attained in that, according to the invention, the center electrode for thermo-technical reasons is built in the chamber in such a manner that it is surrounded by the cool fresh gas forced in through the annular nozzle and through the directed jet nozzles during the compression stroke and is not additionally heated by the protracted sizzling sparks because, as the ignition jet leaves the chamber, these are blown out so that a general cooling of the center electrode on all sides is ensured.

One form of the invention is illustrated in the only figure of the accompanying drawing which shows a chamber spark-plug in elevation with the lower combustion chamber end portion in longitudinal section.

A center electrode 2 extends right through the sparkplug body 1 and is tapered at its lower end where it extends into a conical nozzle 7, thereby forming an annular nozzle having an ignition edge 8.

The insulator is designated by 3, the jet chamber with 4, the directed jet nozzles with 5 and the main combustion chamber wall with 6.

The spark-plug operates in the following manner:

During the compression stroke the fresh gases pass in cool state through the annular nozzle 7 into the jet chamber 4 and cool the center electrode 2 on all sides at its spark producing end. As the cooling current towards the connection end decreases, the directed jet nozzles 5 come into operation and cool the long center electrode 2 in the jet chamber 4. All cooling fresh gas jets flowing in at the sparking end converge in the direction towards the connection end and form a cooling jacket around the center electrode 2.

In the known spark-plugs additional heating is caused by protracted sizzling sparks. These do not occur in the spark-plugs according to the invention because they are blown out by the ignition jet shooting out through the annular nozzle 7. In this connection it must be seen that the chamber 4 is large enough and has a sufiicient number r 2,823,329 patented Feb. 11, 1958 "ice offilling-apertures or nozzles 5 to accommodate a'sutlicient quantityof fresh gas.

By the cooling process which takes place, the center electrode 2- is cooled on all sides, which accounts for the improved and unexpected effect of the new spark-plug.-

'-In-the'-new chamber spark-plug all heat values are-done away with because at the sparking end the fresh gas and the exhaust gas are kept in continuous oscillation between the annular nozzle 7 and the insulator 3, with the result that fouling of the insulator 3 cannot occur. As a consequence the spark-plug is unaffected by different kinds of fuel and diesel oil can also be used without leaving a residue.

Moreover, the resistance to pinking is increased because the source of the pinking is split up by a perfect multiple ignition and practically done away with. Consequently fuel having a low octane content can be used and it is nevertheless possible to obtain a higher compression. The new multi-jet ignition causes a thorough mixing and multiple ignition of the mixture, resulting in more rapid combustion, which in turn gives a higher performance with the same fuel consumption. Consequently it is possible, particularly in the case of two-stroke cycle engines, to reduce fuel consumption considerably.

Another advantage of the new spark-plug is, that sparking trouble no longer occurs and preventative measures are no longer necessary.

I claim: 1. A sparking plug for internal combustion engines,

comprising a sparking chamber having a wall forming part of the wall of the combustion chamber of the engine, said wall being formed with a central opening therein in the form of a nozzle which is of diminishing crosssectional area from the terminus of said chamber towards the interior of said sparking chamber to form an 1nwardly tapered central opening having a length restricted to the thickness of the end wall of said sparking chamber, a central electrode passing through said sparking chamber and into said central opening, said central electrode having an ignition end of conical form which tapers in the opposite direction with respect to said inwardly tapered central opening, whereby ignition occurs simultaneously in said sparking chamber and in the combustion chamber of the engine, said wall of said sparking chamber being formed with a series of openings circumferentially disposed about said central opening and directed inwardly of said sparking chamber and towards the tapered end portion of said central electrode.

2. A sparking plug for internal combustion engines, comprising a sparking chamber having a wall forming part of the wall of the combustion chamber and con sisting of a frusto-conical portion tapering towards said combustion chamber and a fiat base portion extending across the narrow end of said frusto-conical portion, said wall being formed with a central opening in the flat base portion thereof in the form of a nozzle which is of diminishing cross-sectional area from the exterior of said base portion towards the interior of said sparking chamber to form an inwardly tapered central opening having a length restricted to the thickness of said fiat base portion of said sparking chamber, a central electrode passing through said sparking chamber and into said central opening, said central electrode having an ignition end of conical form which tapers in the oposite direction with respect to the taper of said central opening in the base portion of said sparking chamber, whereby ignition occurs simultaneously in said sparking chamber and in said combustion chamber, said wall of said sparking chamber being formed with a series of openings in the frustoconical portion thereof circumferentially disposed about said central opening and directed inwardly of said sparking chamber and towards the tapered end portion of said central electrode.

3. A sparking plug according to claim 1, in which said ycentralelectrode is surrounded by an insulatort which terminates adjacent one end of-sai d'sparking chamber -and wherein said sparkingchamber is formed with a References Cited in the file of this patent UNITED STATES PATENTS Thomas Nov. 4,] 1952 

